The present invention relates to novel single-chain multifunctional polypeptides comprising at least two binding sites specific for the CD19 and CD3 antigens, respectively. The present invention further relates to a polypeptide, wherein the above-described polypeptide comprises at least one further domain, preferably of pre-determined function. Furthermore, the present invention relates to polynucleotides encoding said polypeptides as well as to vectors comprising said polynucleotides and to host cells transformed therewith and their use in the production of said polypeptides. In addition, the present invention relates to compositions, preferably pharmaceutical and diagnostic compositions, comprising any of the afore-described polypeptides, polynucleotides or vectors. A further object of the present invention is the use of the afore-mentioned polypeptides, polynucleotides and vectors for the preparation of pharmaceutical compositions for immunotherapy, preferably against B-cell malignancies such as non-Hodgkin lymphoma.
Several documents are cited throughout the text of this specification. Each of the documents cited herein (including any manufacturer's specifications, instructions, etc.) are hereby incorporated by reference; however, there is no admission that any document cited is indeed prior art of the present invention.
Despite the medical importance, research in B-cell mediated diseases such as non-Hodgkin lymphoma has produced only a small number of clinically usable data and conventional approaches to cure such diseases remain tedious and unpleasant and/or have a high risk of relapse. For example, although high dose chemotherapy as a primary treatment for high grade non-Hodgkin lymphoma may improve overall survival, about 50% of the patients still die of this disease (2-4). Moreover, low-grade non-Hodgkin lymphoma-like chronic lymphatic leukemia and mantle cell lymphoma are still incurable. This has stimulated the search for alternative strategies like immunotherapy. Antibodies directed against cell surface molecules defined by CD antigens represent a unique opportunity for the development of therapeutic reagents.
The expression of certain CD antigens is highly restricted to specific lineage lymphohematopoietic cells and over the past several years, antibodies directed against lymphoid-specific antigens have been used to develop treatments that were effective either in vitro or in animal models (5-13). In this respect CD19 has proved to be a very useful target. CD19 is expressed in the whole B lineage from the pro B cell to the mature B cell, it is not shed, is uniformly expressed on all lymphoma cells, and is absent from stem cells (8, 14). An interesting modality is the application of a bispecific antibody with one specificity for CD19 and the other for the CD3 antigen on T cells. However, bispecific antibodies thus far available suffer from low T-cell cytotoxicity and the need of costimulatory agents in order to display satisfactory biological activity.
Thus, the technical problem underlying the present invention was to provide means and methods useful for the treatment of B-cell mediated diseases such as various forms of non-Hodgkin lymphoma. The solution to said technical problem is achieved by providing the embodiments characterized in the claims.
Accordingly, the present invention relates to a single-chain multi-functional polypeptide comprising
(a) a first domain comprising a binding-site of an immunoglobulin chain or an antibody specifically recognizing the CD19 antigen; and
(b) a second domain comprising a binding site of an immunoglobulin chain or an antibody specifically recognizing the CD3 antigen.